1. Field of the Invention
This invention relates to the treatment of liquids and more particularly it concerns novel structures for straining liquids in liquid treatment systems.
The present invention is particularly useful as embodied in injector type air-liquid contact apparatus such as the evaporative cooling systems shown and described in U.S. patent application Ser. No. 144,853 filed May 19, 1971. These systems are also known as ejector type cooling systems. In such systems, water to be cooled is intimately mixed with atmospheric air and a small portion of the water evaporates into the air with the result that the remaining, major portion, of the water is cooled. Because of the intimate mixing of atmospheric air with the liquids to be cooled a substantial amount of foreign particulate matter carried along by the atmospheric air becomes entrained by liquid and tends to contaminate it.
2. Description of the Known Prior Art
In the past, various straining means have been employed for removing the entrained contaminants from the cooled liquid. In the aforesaid copending application, for example, a strainer screen is positioned across a sump so that it lies perpendicular to the flow of liquid in the sump. Another strainer arrangement but with the strainer still perpendicular to liquid flow is shown in U.S. Pat. No. 1,564,075. In addition, in Australian Pat. No. 268,590, there is shown a strainer which slants in the direction of liquid flow with its upper edge in the downstream direction. While these straining means did perform their straining tasks quite adequately, they did require periodic cleaning or replacement at intervals depending upon the liquid flow rate, the degree of liquid contamination, and the size of the strainer openings.